Since 2004, Manhattan has built 13 skyscrapers that rise to an astounding 700 feet or higher, with another 15 still under construction and 19 proposed. At the same time, there's another skyscraper trend sneaking its way into the skyline—and it has less to do with height and more to do with width. These "super-slenders" are a breed of luxury residential towers that can be as skinny as 45 feet wide.

"Slenderness" in regards to buildings refers to a proportion based on the width of the base to the height of the building—any skyscraper with a minimum 1:10 or 1:12 ratio of width to height is considered slender. In New York, there are 18 buildings, all of them luxury residences, that meet the criteria. As Dezeen first pointed out, the Skyscraper Museum has created an interactive chart that lines them all up, starting with the 2008 Sky House—both the earliest and the shortest of the group—and ending with the tallest, the still under-construction Central Park Tower.

As the museum notes on its site, slender buildings are subject to a 1961 zoning law that set a maximum total floor area permitted on a given lot, measured by the Floor Area Ratio (FAR). The law was meant to set a limit on building height, but it also provided a loop-hole by creating the concept of "air rights." Essentially, a developer can buy the air rights from an adjacent building that has not used all of the FAR permitted to that lot. All of the "super-slenders" above used that method of transference to get their height.

Of course, the height of slender buildings pales in comparison to the world's tallest skyscrapers, and the Skyscraper Museum put together another chart to illustrate just how much, above. In general, super-tall buildings are becoming a reality for more New Yorkers as well, as Michael Kimmelman writes in a fascinating story in The New York Times this week.

Yet, as property values continue to soar in New York, it's easy to see why super-skinny buildings are increasing in popularity. Move over 1WTC—in this city, there's always something new to aspire to.